btcpayserver/BTCPayServer/Views/Shared/LayoutPartials/NotificationsNavItem.cshtml

<div></div>
@await Component.InvokeAsync("NotificationsDropdown")
<script>

var supportsWebSockets = 'WebSocket' in window && window.WebSocket.CLOSING === 2;

if (supportsWebSockets) {
    var ws_uri = "@Url.Action("SubscribeUpdates", "Notifications", new {}, Context.Request.Scheme)".replace("http", "ws");
    var newDataEndpoint = "@Url.Action("GetNotificationDropdownUI", "Notifications", new {}, Context.Request.Scheme)";

    try {
        socket = new WebSocket(ws_uri);
        socket.onmessage = function (e) {
            $.get(newDataEndpoint, function(data){
                $("#notifications-nav-item").replaceWith($(data));
           });
        };
        socket.onerror = function (e) {
            console.error("Error while connecting to websocket for notifications (callback)", e);
        };
    }
    catch (e) {
        console.error("Error while connecting to websocket for notifications", e);
    }
}

</script>